This invention is concerned with an ergonomic chair which provides for stimulation of the hips while the user is seated, to at least partially simulate the hip motion involved in walking, thus reducing posturally caused lower back pain and stiffness.
Sitting for long hours, whether driving, working at a computer, traveling or other activities, has become a contributing factor to lower back pain, stiffness, and degenerative disk disease. The problem with sitting in a standard single seat chair is that after a few minutes, the pressure of the torso's gravitational weight on the sacrum, the triangular shaped bone between the two iliac bones, begins to lock not only the sacroiliac joint, but also the acetabular joint which houses the femur bone of the leg. Once the sacrum beings to lock, or fixate, at the sacroiliac joints, the lower lumbar spine also beings to immobilize.
The results of this occurrence include the stasis of cerebral spinal fluid in the sacral reservoir of the sacrum, as well as the loss of vital motion of both the ligaments and musculature, therefore causing increased pressure on the lumbar disks. Cerebral spinal fluid originates in the central ventricles of the skull. The fluid is then pumped out of the skull, into the spinal column and down into the sacral reservoir in the center of the sacral bone in the pelvis. The full cycle of the flow of cerebral spinal fluid takes twelve to fifteen seconds. In osteopathy, this cycle is known as the primary respiratory motion.
The mechanism of the pumping of the cerebral spinal fluid is a combination of the movement of the cranial plates in the skull, the intracranial dura mater, and the spinal dura. In order for this entire mechanism to function properly, there must be a return of cerebral spinal fluid (CSF) pumped out of the sacral reservoir. This crucial return of cerebral spinal fluid is contingent on the ability of the sacrum to move in its pitch, roll and yaw range of motion. A decrease or loss of motion of the sacrum leads to inadequate return of CSF back up the spine. Any backup of CSF creates intradural pressure in the lumbar spine, causing the nerve roots to be particularly vulnerable to irritation of inflammation. And, irritation of the lower back nerve roots or ligamentous structures results in compensatory muscle contraction. Based on the premise that the structure of the pelvis influences the function of cerebral spinal fluid flow, it is vital to maintain adequate motion of the structures of the lower spine and pelvis. This necessary mobility will prevent chronic and acute conditions of the lower spine.
Chairs with moving seat elements, which may be motorized or otherwise driven for the purpose of relieving fatigue and simulating some of the hip motion of walking, have been known. Harza U.S. Pat. No. 5,588,704 shows a rocking platform incorporated in a seat, causing one hip to be lifted and then the other in a rhythmic manner while the person is seated. The disclosed apparatus also allows for forward and backward movement of each hip. Harza U.S. Pat. No. 5,022,385 is directed at a similar goal, but using air bags and a pneumatic pump for rocking the two hips up and down in opposition.
Other patents which show power seat mechanisms, but not with the purpose of hip stimulation, include U.S. Pat. Nos. 5,314,238, 5,709,363, 5,735,573 and 5,751,129.
Although the Harza patents cited above show chair mechanisms having moving seat components and directed at some of the purposes of the present invention, none of the above patents contemplates either the efficient mechanism or the type of motion which stem from the present invention.